Setting Tool Power Charge Initiation

ABSTRACT

A power charge for a packer setting tool includes an outer casing and an amount of flammable material within the casing. A heating igniter is retained within the outer casing in contact with the flammable material. The heating igniter is energized by electrical power to heat it to a temperature that is sufficient to ignite the flammable material.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention relates generally to devices and methods for initiating orsetting off a power charge within a wellbore.

2. Description of the Related Art

Power charges are used to generate gases needed to apply compressiveforce for an affixed setting tool. A typical use for a power charge isas the motive force for a wireline setting tool. Such a setting tool isused to set bridge plugs, cement retainers and production packers orother downhole devices which must be anchored within a wellbore. Powercharges are typically initiated by an igniter which uses electricalcurrent to detonate a small amount of explosive material. A jet of hotburning gases created by the igniter will detonate a secondary pelletwhich, in turn, initiates the setting tool.

Some conventional igniters have reliability problems. A nichrome wirewhich is in contact with black powder within the igniter tends to suffercorrosion. As a result, there can be an unacceptable failure rate forsuch igniters after one year of shelf life. These conventional ignitersare usually rated as explosive material, requiring special packaging andhandling and thus increasing costs and delivery times.

SUMMARY OF THE INVENTION

The invention provides improved systems and methods for initiating apower charge when the setting tool is within a wellbore. Power chargesare described which include at least one heating igniter which isnon-explosive and which detonates the power charge by generating a hightemperature which is sufficient to cause the flammable material withinthe power charge to ignite. Electrical voltage is supplied to theigniter to energize it. In preferred embodiments, electrical current isprovided from the surface via wireline. In one embodiment, the igniteris a resistive heating element. In an alternative embodiment, theigniter is an uninsulated coil of wire.

In accordance with preferred methods of use, a power charge containing aheating igniter is incorporated into a packer setting tool. The packersetting tool and an affixed packer device are then run into a wellboreusing a wireline running string. When the packer device is at a locationwherein it is desired to set the packer device, the power charge isdetonated by energizing the heating igniter thereby setting the packerdevice within the wellbore.

BRIEF DESCRIPTION OF THE DRAWINGS

For a thorough understanding of the present invention, reference is madeto the following detailed description of the preferred embodiments,taken in conjunction with the accompanying drawings, wherein likereference numerals designate like or similar elements throughout theseveral figures of the drawings and wherein:

FIG. 1 is a side, cross-sectional view of an exemplary wellborecontaining a packer device and packer setting tool in accordance withthe present invention.

FIG. 2 is a side, cross-sectional view of portions of the setting toolfrom FIG. 1 and related components, including a power charge inaccordance with the present invention.

FIG. 3 illustrates an exemplary power charge igniter constructed inaccordance with the present invention.

FIG. 4 illustrates an alternative embodiment for a power charge igniterconstructed in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 depicts an exemplary wellbore 10 which has been drilled throughthe earth 12 from the surface 14. The wellbore 10 is lined with metalliccasing 16. A tool string 18 is shown disposed into the wellbore 10. Thetool string 18 includes a wireline running string 20 from which issuspended a packer device 22. The packer device 22 may be acompression-set packer of a type known in the art. In the depictedembodiment, the packer device 22 includes an elastomeric packer element24 which is expanded radially to set against the casing 16 by axialcompression.

The packer device 22 is affixed to a packer setting tool 26. The packersetting tool 26 is operable to set packer device 22 by applyingcompressive force to portions of the packer setting tool 26. Exceptwhere otherwise described herein, the packer setting tool 26 can beconstructed and operated in the same manner as the E-4 packer settingdevice which is available commercially from Baker Hughes Incorporated ofHouston, Tex.

FIG. 2 illustrates portions of the packer setting tool 26 in greaterdetail. The packer setting tool 26 includes an outer housing 28 whichdefines a recess 30 for retaining power charge 32. A piston 34 isretained within the housing 28 and is axially moveable therein. As isknown, movement of the piston 34 with respect to the housing 28 willcause setting of the packer device 22.

The power charge 32 includes an outer casing 36 which contains an amountof flammable material 38. The flammable material 38 may be made up usingdifferent recipes or mixtures, as is known in the art, to allow burningat various rates to allow optimum setting times for different types ofpacker devices. The flammable material 38 is a material in the solidphase of matter that can readily undergo combustion in the source ofignition under standard circumstances, i.e., without artificiallychanging variables such as pressure or density or by adding accelerants.Flammable material is readily combustible. It may cause or contribute tofire through friction. Readily combustible materials can be powdered,granular or pasty chemicals which are dangerous if they can be easilyignited by brief contact with an ignition source. Flammable material 38is very energetic and produces high temperature gaseous products oncombustion which leads to high energy density needed for producing therequired propulsive force. Flammable material 38 can consist of severalchemical ingredients such as oxidizer, fuel, binder, plasticizer, curingagent, stabilizer and cross-linking agent. The specific chemicalcomposition depends on the desired combustion characteristics for aparticular application. Different chemical ingredients and theirproportions result in different physical and chemical properties,combustion characteristics and performance. The outer casing 36 isshaped and sized to reside within the recess 30 in a complementarymanner. A heating igniter 40 is also contained within the casing 36 incontact with the explosive 38. Electrical conduit 42 is interconnectedwith the heating igniter 40. The electrical conduit 42 will extendupwardly along the wireline 20 to an electrical power source 44 (FIG. 1)at surface 14. The electrical power source 44 may be a generator,battery or other source of electrical energy which is sufficient toprovide energizing power to the heating igniter 40.

FIG. 3 illustrates an exemplary heating igniter 40 in greater detail.The depicted heating igniter 40 is a metallic resistive heating elementwhich will heat up when electrical current is applied to it. Theresistive heating element is preferably made of stainless steel.However, it might also be fashioned from a bimetallic or non-metallicmaterial or other suitable materials. In the depicted embodiment, theresistive heating element is rod shaped. However, it should beunderstood that the resistive heating element may have other shapes.When energized, the heating igniter 40 should achieve a temperature thatis sufficient to reach the ignition temperature of the flammablematerial 38. This temperature may be in the range of from about 750° F.to about 900° F. Most preferably, the temperature is about 800° F.

FIG. 4 illustrates an alternative embodiment for an igniter 40′ inaccordance with the present invention. The heating igniter 40′ is a coilof wire. Current power supplies in the field will provide about 200volts of electrical power and 1 to 1.5 amps. That power can be used forup to about 10 seconds. Wire size can be varied to provide differentwatt densities, output temperatures and the like to adjust for differentflammable material 38.

In an exemplary method of operation, the packer setting tool 26 andpacker device 22 are run into the wellbore 10 on wireline running string20. When the packer device 22 is at a location wherein it is desired toset the packer device 22 within the wellbore 10, the packer setting tool26 is actuated by initiating the power charge 32 within. Initiation ofthe power charge 32 is done by energizing the heating igniter 40 or 40′.

Because heating igniter 40 or 40′ is non-explosive, it is believed thatuse of them will provide improved safety and reduced costs. Those ofskill in the art will recognize that numerous modifications and changesmay be made to the exemplary designs and embodiments described hereinand that the invention is limited only by the claims that follow and anyequivalents thereof.

What is claimed is:
 1. A power charge for a packer setting tool, thepower charge comprising: an outer casing, the casing being shaped andsized to reside within a power charge recess within a packer settingtool; an amount of flammable material within the casing; and anon-explosive heating igniter retained within the casing and in contactwith the flammable material, the heating igniter being energizable byelectric power to reach a temperature sufficient to ignite the flammablematerial.
 2. The power charge of claim 1 wherein the heating ignitercomprises a metallic resistive heating element.
 3. The power charge ofclaim 1 wherein the heating igniter comprises a coil of wire.
 4. Thepower charge of claim 1 wherein the heating igniter is formed ofstainless steel.
 5. A packer setting tool for setting an associatedpacker device within a wellbore, the packer setting tool comprising: asetting tool housing; a piston which is axially moveable with respect tothe setting tool housing, movement of the piston being effective to setthe associated packer device; a power charge retained within the settingtool housing, the power charge having an outer casing, the casing beingshaped and sized to reside within a power charge recess within a packersetting tool; an amount of flammable material within the casing; and anon-explosive heating igniter retained within the casing and in contactwith the to flammable material, the heating igniter being energizable byelectric power to reach a temperature sufficient to ignite the flammablematerial.
 6. The packer setting tool of claim 5 further comprising anelectrical conduit which interconnects the heating igniter with anelectric power source.
 7. The packer setting tool of claim 5 wherein theheating igniter comprises a metallic resistive heating element.
 8. Thepacker setting tool of claim 5 wherein the heating igniter comprises acoil of wire.
 9. The packer setting tool of claim 5 wherein the heatingigniter is formed of stainless steel.
 10. A method of setting a packerdevice within a wellbore, the method comprising the steps of: disposinga packer device and associated packer setting device into a wellbore,the packer setting device including a power charge with a non-explosiveheating igniter; detonating the power charge by energizing the heatingigniter with electric power.
 11. The method of claim 10 wherein theheating igniter is energized by a power source which is located at asurface location with respect to the wellbore.